and then another asteroid hit russia. and if that meteor was delayed by two or three seconds, it would have been a ground burst rather than an air burst and at 40,000 miles per hour do the math it's 20 hero sheema bombs. -- her -- hiroshima bombs. >> stephen: i'm happy do you the math. how often is this happen something in. >> we didn't have large metropolises hundreds of years ago, we had fishing vil yanlz they hit the earth before. we were oblivious, blissfully unaware that we had near misses and actual collisions with objects about the size of an apartment building. these are city buses. and then we have a nation buster which is going to come grazing past the earth and may even hit the earth. that's called the asteroid apofet. it's ten times bigger than the asteroid that scimed the earth last week. >> stephen: what do you mean may hit? what is the -- do the math. [ laughter ] what is the math on that one? >> well, first it's going to skim by the earth in 2029 and it's going to graze the atmosphere. that's the question mark. we don't know how much friction it's going to encounter. that cannot
